This invention relates to a novel growing medium for seeds, plants, etc. More particularly, this invention concerns a novel growing medium for the propagation of seeds, cuttings, plants etc., Containing a product obtained from combusting essentially the bark obtained as a wasteby-product in the processing of logs into useful materials, e.g. pulp for paper products, etc.
With the diminishing availability and/or practicality of good natural soils, the need for economic materials serving to replace all or part of the natural soil component of growing media has become all the greater. Moreover, ordinary soil is often deficient in one or more aspects, requiring the addition of further materials or "amendments" thereto in order to overcome these deficiencies.
It is in the area of container growing in particular that ordinary natural soils are found most often deficient. When seeds, seedlings, cuttings, etc. are grown in pots, trays or other containers, ordinary soils are often found unsuitable as growing media, particularly when such growing is being done on a commercial scale by relatively large growers. Ordinary soil is often too heavy in weight, to little aerated, and lacking in sufficient moisture holding ability. On drying, ordinary natural soil often tends to skrink away from the sides of containers, with the results that water from consequent waterings runs down the sides of the container and out of the drainage holes without complete wetting of the soil. Such drawbacks have obvious undesirable consequences for commercial growers in particular. Excess weight increases handling and transportation costs, and is very undesirable in instances where the container-grown plants are placed upon roofs, patios, etc. of buildings. Shrinkage of the soil results in an undersirable appearance to the ultimate purchaser of the container grown plant and can affect the roots of the plants if great enough. The need for more frequent waterings of insufficiently wetted soils increases costs, and can also be a drawback when the plants are shipped long distances in their containers.
Ideal growing media is well aerated and retentive of moisture, yet at the same time is sufficiently dense to hold seedlings and plants in place. Adequate nutrients need be present for young plantings especially, without high levels of salinity which might damage germinating seeds. The media should also be sterile, that is, free from insects, nematodes and harmful bacteria and fungi.
These requirements have traditionally been met by mixtures of sterilized loam, sand and peat, supplemented by appropriate lime and fertilizer. The so-called "John Innes" composts are of this type. As good natural loam has become scarce, loamless or "soilless" compositions have been developed which are mixtures of sand and peat, expanded vermiculite and peat moss, or such mixtures along with shredded bark, composted bark humus, perlite, etc. Measured amounts of nutrients and trace elements are usually also included.